The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Do I Need to Increase My Mounjaro Dose?
Whether you need to increase your Mounjaro dose depends on your individual response to the medication and your prescriber's clinical assessment. Mounjaro uses a structured dose titration schedule, starting at 2.5 mg and escalating every 4 weeks up to a maximum of 15 mg weekly. Your GP or prescriber will monitor your progress and assess whether dose adjustment is appropriate for you. This differs from other weight loss injections like Wegovy, which has its own distinct escalation timeline. Use our GLP-1 weight loss calculator to understand projected outcomes at different dose levels, and your prescriber will personalise your treatment plan.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
Mounjaro Dose Titration vs Wegovy — Key Differences
Mounjaro (tirzepatide) and Wegovy (semaglutide) follow different dose escalation patterns. Mounjaro typically starts at 2.5 mg and increases by 2.5 mg increments every 4 weeks: 2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mg. Wegovy begins lower at 0.25 mg and escalates in smaller steps over 16 weeks to reach 2.4 mg. Clinical trial data shows Mounjaro (SURMOUNT trial) achieved average weight loss of 15–21% at maximum doses, whilst Wegovy (STEP trial) achieved approximately 15% on average. The key difference is mechanism: Mounjaro is a dual GIP and GLP-1 receptor agonist, whilst Wegovy is GLP-1 only. Your prescriber determines whether continued dose escalation is appropriate based on your response, side effects, and health goals.
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How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
When Your Prescriber May Recommend Dose Increases
Your prescriber reviews whether to increase your Mounjaro dose based on several factors: your weight loss progress, tolerability of side effects, and whether you're reaching your health targets. If you're not experiencing significant nausea or gastrointestinal side effects, and you have capacity to escalate, dose increases typically continue on schedule. However, if side effects are severe, your prescriber may pause escalation or maintain your current dose longer. It's important to communicate honestly about any side effects. The decision to increase is always individualised—some people achieve their goals at lower doses (5–10 mg), whilst others benefit from reaching 15 mg. Your GP or prescriber has your complete health picture and can advise what's right for you.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
How often does Mounjaro dose increase?
Mounjaro increases every 4 weeks if tolerated. You stay on each dose for a minimum of 4 weeks before escalating by 2.5 mg. If side effects are significant, your prescriber may extend the time at each dose level or maintain your current dose longer.
What's the maximum Mounjaro dose in the UK?
The maximum licensed dose of Mounjaro is 15 mg once weekly. Some people achieve their weight loss and health goals at lower doses. Your prescriber will decide the right maintenance dose for you.
Can I stay on a lower Mounjaro dose if it's working?
Yes, absolutely. If you're seeing good weight loss results, managing side effects well, and reaching your health goals at 5 mg, 7.5 mg, or 10 mg, there's no requirement to escalate further. Dose is individualised.
How does Mounjaro dose compare to Wegovy?
Mounjaro's maximum is 15 mg weekly, whilst Wegovy maxes at 2.4 mg weekly. These aren't directly comparable due to different mechanisms (dual GIP+GLP-1 vs GLP-1 only). Your prescriber chooses based on your suitability and health needs.
What if Mounjaro side effects are too severe to increase dose?
Tell your prescriber immediately. They may keep you on your current dose, reduce it, or suggest an alternative. Side effects like severe nausea or vomiting warrant medical review. Never adjust your own dose.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.